Abstract

We have investigated the cellular localisation of GABAA (GABAAR) and glycine (GLYR) receptors in the human basal ganglia using immunohistochemical techniques and light and confocal laser scanning microscopy. GABAAR were most highly expressed on GABAergic striatal interneurons (α1, β2,3, γ2 subunits), cholinergic interneurons (α3), and striatal projection neurons (α2, α3, β2,3, γ2 subunits). GLYR were present mainly on ChAT and a subset of parvalbumin striatal interneurons. The neurons of the globus pallidus (GP) showed high levels of α1, α3, β2,3, γ2 subunits (no α2) whereas GLYRs were only distributed on a subpopulation of pallidal neurons. In addition, GLYRs selectively stained neurons in the intermedullary laminae of the GP. Neurons in the SNr and SNc were labelled with GLYR but had different GABAAR subunit configurations. SNr neurons expressed α1, α3, β2,3, γ2 (no α2) subunits and SNc neurons expressed mainly GABAAR α3γ2 subunits. These results demonstrate that in the basal ganglia, neurons are generally associated with one of four different GABAA receptor configurations. This suggests that throughout the basal ganglia GABA acts via GABAA receptors with various subunit combinations and that glycine acts through glycine receptors on neurons of the SNr and SNc and groups of interneurons scattered throughout the striatum and GP.

Notes

Acknowledgements

This work was supported by grants from the Neurological Foundation of New Zealand and the Health Research Council of New Zealand. KB is grateful for support from the British Royal Society. We thank the Neurological Foundation of New Zealand Human Brain Bank for providing the human brain tissue used in these studies. We also thank the Biomedical Imaging Research Unit (BIRU) in the Department of Anatomy with Radiology University of Auckland for expert assistance and use of their facilities.